A conventional drip irrigation system as disclosed in U.S. Pat. No. 4,307,841 comprises a thermoplastic conduit having substantially discrete emitter units (3) heat welded to axially spaced apart locations of an inner surface of the conduit adjacent outlet apertures formed in the conduit, allowing irrigation liquid to flow through the groove (10) and the flexible membrane (17) to be substantially pressureless drips discharging through the apertures (2).
However, such a conventional drip irrigation system has the following drawbacks:
1. The groove (10) is corrugatedly formed in each emitter unit (3) and so many emitter units (3) must be fixed in the irrigation conduit, thereby increasing the installation inconvenience and the production cost. PA0 2. The flexible membrane (17) is retained by the flanges (14) to constitute an emitter cover to define a flow restricting flowpath with the elongated groove (10), not for filtering the irrigation liquid, thereby lacking of water filtration effect. PA0 3. The irrigation liquid does not flow through (penetrate into) the flexible rubber membrane (17) in order to greatly reduce the fluid pressure due to friction loss. So, the reduction of fluid pressure relies upon the elongated groove (10) which is corrugatedly formed in the base of the emitter unit as shown in their FIG. 2, thereby increasing the production complexity and cost.
The present inventor has found the drawbacks of conventional drip irrigation system and invented the present water-penetrable drip irrigation pipe.